Medical information for patients

Heavy periods (menorrhagia)

Heavy periods (menorrhagia) affect many women. However it is difficult to be sure what people mean by heavy periods. Heaviness of periods is very subjective. As with many other bodily functions, that which is considered perfectly normal by some might be thought extremely abnormal by others.


An average amount of blood loss during a period (menses, menstruation) is 30 to 40ml (six to eight teaspoons). Measurement of the exact amount of blood lost is very difficult. (Researchers have to weigh new and used sanitary towels, but this is not the sort of thing most of us would want or need to undertake!)

When you are losing excessive amounts of blood, you may keep passing large clots (like liver) and you may need to change sanitary towels or tampons very frequently.

Women vary in how long it is from the start of one period to the next. In some it is less than a month and others it is longer. Some have an irregular pattern. The actual length of the period varies too, and may be from three to seven days. In menorrhagia, some women have very prolonged blood loss, with only days before the next episode.

Heavy periods may be accompanied by cramp-like period pain, but some women find even their heavy periods painless. (The medical term for painful periods is dysmenorrhoea.)

Persistent heavy periods can lead to thinning of the blood (anaemia), which can cause tiredness, shortness of breath, faintness, and even angina. Symptoms of this sort would usually prompt people to see the doctor anyway.


Many times there is no particular cause to be found. Sometimes a structural irritation in the womb is to blame, such as a quite common condition where there are localised areas of overgrowth of the muscle wall of the womb (fibroids or fibromyomas), and when there is a coil (or Intra Uterine Device) in the womb.

Heavy periods are more common after sterilization, and happen more in women who are overweight, and also with certain hormonal upsets.


You should see your doctor if your periods are disrupting your life. Another point to discuss with your doctor is if you get even light bleeding or "spotting" between periods or after intercourse.

Your doctor is likely to examine you internally to check on the womb and the ovaries. At that time you may well have a (PAP) smear taken. Occasionally a sample of the lining of the womb is taken at the time of an internal (vaginal) examination.

The doctor may arrange a blood test to check for anaemia, and possibly for other tests such as thyroid and the reproductive hormones.

If necessary, your doctor may arrange for you to see a specialist (gynaecologist).


If you are anaemic, you may need to take extra iron, which your doctor may prescribe, but which may work out cheaper if you buy it over the counter from a pharmacy.

There are medications which can cut down the blood loss. Some of these do not use hormones, and merely work on the way in which the blood clots. Many people see that as an advantage. Some pain relieving anti-inflammatory drugs which people take for period pain do actually cut down blood loss as well.

Other treatments stop the bleeding, but do so by affecting your hormone levels (for example adding progesterone).

Your doctor might suggest an intrauterine contraceptive device (IUCD) which contains progesterone (Mirena). This is a very effective form of contraception, but also helps to reduce blood loss in heavy periods.

The oral contraceptive pill tends to lead to lighter bleeds, which come regularly, and some people find this is the answer for them. There are also hormone treatments which can stop you having periods all together; this may be in tablet form or by injection.

If all else fails, and the symptoms drive you to it, an operation to remove your womb (hysterectomy) is an option, and more recently an operation using lasers or microwave technology has been used to remove the lining of the womb (endometrium), which is the part that bleeds, while leaving the rest of the womb behind.

Further information


The New Harvard Guide to Women's Health, by Karen Carlson MD, Stephanie Eisenstat MD, Terra Ziporyn PhD
A book written by women doctors for women.

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